1. Field of the Invention
The present invention relates to an image capturing apparatus and an image capturing method for sending out time-varying image data onto a network.
2. Description of the Related Art
Recently, the Internet has widely spread, and transmission of information by WWW (World Wide Web) and the like is commonly performed. In such a situation, there has appeared an image capturing apparatus provided with a function of capturing an image in real time and transmitting the picture (a time-varying image) onto a network. Network Camera Server VB-C10 by Canon Inc. is a good example thereof.
When it is attempted to provide services for users via a network, there may be a case where encoded data which have been processed with multiple different parameters are requested, for one input image taken at some time point, because users' requests are varied. As a first example of an image processing apparatus attempting to respond to such requests, there exists an image processing apparatus attempting to respond to the requests by having multiple encoding processing units (for example, Japanese Patent Laid-Open No. 2003-309853 (p. 19; FIGS. 1 and 6; p. 20; FIG. 3)).
Thus, in the case of attempting to respond to multiple image processing requests by having multiple encoding processing units, the content of services which can be provided is restricted by the number of the processing units. By increasing the number of the processing units, the restriction may be loosened. However, a network camera server and the like, which has an image capturing function, are generally required to be small-sized, and the number of processing units which can be implemented therein is restricted by the board/chip area or the heat value thereof. Therefore, there is a problem that the number of processing units is actually limited.
Meanwhile, in the case of capturing an image in real time and accumulating images for the purpose of monitoring or delivery, it is never allowed to drop an image inputted from an image capturing apparatus. For example, in the case of acquiring a picture input from a video camera for capturing images at a rate of 30 frames per second, the time allowed for processing any given frame is 1/30 second in principle, which is the time required for inputting one frame image. The time required for inputting one frame image is hereinafter referred to as “one picture period”. A system is required to respond to a wide variety of users' requests described above within the picture period. A network camera capable of remotely operating a picture taking unit is required to operate in real-time and have little delay.
As a second example of an image processing apparatus, there exists an image processing apparatus attempting to respond to various users' requests by reading various conversion algorithms stored in a ROM in advance as necessary, and causing a DSP to perform the processing of the algorithms (for example, Japanese Patent Laid-Open No. 06-125411 (p. 8; FIG. 1; p. 10; FIG. 4)).
In this technique, multiple image processing operations are simply performed by the DSP in parallel in a time-sharing manner in accordance with the algorithms, and there is a problem that the processings are not assured to be completed within one picture period.
That is, a prior-art image capturing apparatus that sends out time-varying image data onto a network has a difficulty providing multiple services for users who issue various requests on a network while maintaining a real-time operation.